Optical phase modulators have numerous applications such as: active mode locking of a laser, stabilization of a laser frequency, wavelength tuning of a single-frequency laser, enabling a core technology for interferometers, generating frequency combs for some metrology applications, or other applications. Dynamically changing a phase of light can be achieved by, for example, dynamically changing a length of a light path (e.g., stretching a waveguide), or by dynamically changing a refractive index of a medium in which light travels. The refractive index of a medium can be changed by, electric field, magnetic field, stress field, temperature, quantum-confined Stark effect, free-carrier plasma dispersion, or other means. However, dynamically changing a length of the light path is a mechanical process, and therefore it is energy inefficient and slow. An ability to dynamically change the refractive index in some materials is limited and may be difficult.